Experimental Study On Scour Around Submarine Pipelines In Sloped Seabed Under Wave Action

Petroleum transmission pipelines on the Slope seabed are with extremely bad ocean environment, once accident happens, there will be great economic loss and environmental pollution.Long pipe near the bed surface under wave action is easily to be washed, leading to local impending,which is security risks for pipeline.Therefore, further study of bed scour around the pipeline which is on the slope seabed is very important for pipeline safe operation.In this paper studies, the slope of the seabed laid 1:15 is presented,which uses the prototype sand and median diameter of 0.52mm outside diameter of 50mm PVC tube simulation oil pipeline in multifunctional water tank.By wave probe measurement along the wave of change, using three-dimensional topography and profile current meter measurement section before and after the surrounding terrain and pipes under wave velocity.By measuring and calculating the average wave height along, the depth of the pit behind the tube, bar and bunkers, the distance to the slope toe, in order to analyze the sandy seabed slopes wave elements and pipe produced by the change of bed surface morphology evolution cycle scour the influence of the pipes.Research results show that on the sandy seabed slopes, with the scour pipe on the farther distance from slope foot, namely pipeline shelve location ?=h0/h water depth and water depth in deep water ratio is smaller, tube after the maximum increase with the decrease of the first of the suour pit;Pipe tabled at ?=0.47, after the maximum is about 0.2 times the diameter of the scour pit, minimal impact on the tube after flushing;Pipeline tabled at ?=0.36, bar distance along recently, may cause adverse effects in the offshore buildings;Pipes buried in the depth of the water ratio 0.43 location, aside from the pipe to the whole process of buried it can be seen that pipeline first increases then decreases, the maximum distance of the scour pit pipeline buried depth on the bar and movement direction is affected by the bunker;The depth of the water in the deep of 35cm, the ratio of the average wave height and water depth is less than 0.35, the tube increases with the cycle of the pit after deepen and is not affected by surf zone formation sand grain and bar;Cycle is small, the surf zone of sand and sand pit occurs only offshore movement, the period T acuity 1.0s, scour pit sand grain after exposure to the tube and bar forward reduce scour pit may even be bar buried;From buried aside-half buried-all available, due to the tube of the vortex, line in front of the instantaneous velocity turbulence intensity gradually weakened.